My Oil Pressure Gauge does not seem to be working properly. It raises to about 70 upon initial start. As the engine warms it lowers down to around 40, but bounces up and down from 20 to 60. If the truck is at idle for a while it will stabilize for a short while then start bobbing out of control again. I have noticed that over time the idle of the truck just doesnt sound correct. The idle tends to remind me of a farm tractor sound, like blah blah blah, and it seems that it wouldnt take much to make it die. However, I noticed that when the truck idles like this, the gauge bobbing moves with the idle. Could anyone lead me to a solution? Thanks

 

Pressure fluctuations based on rpm's is normal and from your description it sounds like the issue is with the engine idle speed rather than the oil pressure gauge. When was the last complete tune-up?